1. Field of the Invention
The present invention relates to an optical sensor preferably used in an input device for moving a pointer or the like on a screen of a personal computer or the like or in an input device for an electronic game machine, and more specifically relates to a one-dimensional or a two-dimensional optical sensor for sensing the movement of a control arm section maneuvered by the operator in a wide range of angles with a high resolution.
2. Description of the Related Art
Conventional pointing devices as an input device for moving the pointer on the screen of a computer or the like include a joystick and a button type pointing device.
FIG. 17 is an isometric view of a conventional joystick 8. When a stick or control arm 1 moves in an X direction, the movement of the stick 1 is conveyed via a guide 2 and a shaft 3 to a rotary encoder 4 for detecting a rotation direction and a rotation distance. Based on a detection signal from the rotary encoder 4, the rotation direction and the rotation distance of the stick 1 in the X direction are detected. Also, a movement of the stick 1 in a Y direction is conveyed to a rotary encoder 7 via a guide 5 and a shaft 6. Based on a detection signal from the rotary encoder 7, the rotation direction and the rotation distance of the stick 1 in the Y direction are detected.
With reference to FIGS. 18A and 18B, the principle by which the rotary encoders 4 and 7 detect the rotation direction and the rotation distance will be described. When a shaft 11 rotates in association with the movement of the stick 1, a rotatable plate or disk 12 connected to the shaft 11 rotates. The rotatable plate 12 has a plurality of slits 13 formed radially. The rotatable plate 12 is interposed between two light emitting elements 9 and two light receiving elements 10. Light emitted from the light emitting elements 9 is transmitted through the slits 13 as a pulse signal which is converted into an electric signal by the light receiving elements 10. As a result, the rotation direction and the rotation distance of the stick 1 in the X and Y directions in accordance with the counts of the pulse signal are electrically detected.
On the screen of the computer which includes the joystick 8 as a part of the input device, the pointer moves in accordance with the electric signal which indicates the rotation direction and the rotation distance of the stick 1 in the X and Y directions.
FIG. 19 shows a conventional button type pointing device 20 usable as an input device. The button type pointing device 20 includes a button-shape tiltable operation section 18, a holder 20a provided below the operation section 18, a base plate 16 supporting the holder 20a from a bottom surface of the holder 20a, and a sensor section 15 attached to a bottom surface of the base plate 16. The holder 20a includes an elastic section 17 provided below the operation section 18 and having a depression for attachment of a reflective body in a central part of a bottom surface thereof, and a reflective body 19 provided in the depression. The elastic section 17 and the reflective body 19 are formed integrally.
In the button type pointing device 20 having the above-described structure, when the operation section 18 is inclined, the elastic section 17 is elastically deformed. The reflective body 19 formed on the elastic section 17 is also inclined in the same direction, and the inclination of the reflective body 19 is detected by the sensor section 15. A detection signal output by the sensor section 15 is converted into an electric signal and output. In accordance with the electric signal, the pointer on the screen moves.
FIG. 20 is an enlarged view of the sensor section 15. The sensor section 15 is an optical sensor including a light emitting element 15a and light receiving elements 15b provided above the light emitting element 15a. A lens 22 is provided above the light receiving elements 15b. In FIG. 20, reference numeral 23 denotes a secondary mold.
The conventional joystick 8 involves the following drawbacks when being used in an input device.
(1) The rotary encoders 4 and 7 each include the rotatable shaft 11. A space for accommodating the rotation of the shaft 11 needs to be provided, and thus it is difficult to completely seal the rotary encoders 4 and 7. This provides easy access for dust, which may undesirably clog the slits 13. Accordingly, malfunctions can occur relatively easily and thus the reliability is not sufficient.
(2) Since the number of the slits 13 which can be formed in the rotatable disk 12 is limited, the resolution for sensing is also limited.
(3) Two-dimensional detection of the movement of the stick 1 requires provision of rotary encoders in both the X and Y directions. Such an increase in the number of components hampers the size reduction of the apparatus including the joystick 1, and is also against space-saving.
The conventional button type pointing device 20 has the following drawbacks when being used in an input device.
(1) Due to the use of the sensor section 15 which does not require a rotatable shaft, the button type pointing device 20 can be sealed and thus is substantially free of malfunction caused by dust, like in the case of the joystick 1. However, the button type pointing device 20 has a relatively narrow range of detection angles of .+-.10 degrees due to the structure thereof and cannot perform wide-range sensing. Since the reflective body 19 is a plane mirror, when the angle of inclination of the reflective body 19 in association with the operation section 18 is excessively large, the light reflected by the reflective body 19 is not effectively guided to the light receiving elements 15b.
In the case of the button type pointing device 20 which is used in an input device of a game machine, the operation section 18 needs to be movable over a wide range of angles so as to increase the fun of playing, especially for young children.
In the conventional button type pointing device 20 which cannot provide a satisfactory level of wide-range sensing, the operability of the operation section 18 is also restricted. Improvement on this point is required in order to provide a more satisfactory input device for a game machine.
(2) The sensor section 15 requires a lens 22 such as an objective lens for collecting light and also requires the secondary mold 23. Such additional elements unavoidably increase the thickness of the sensor section 15 as indicated by t1 in FIG. 20, which is an obstacle in reducing the size of the sensor section 15.
Accordingly, it would be desirable to have a pointing device as an input device that moves through a wide range of motion and has increased sensitivity and a more compact size.